As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
Conventional stand alone “monoblock” style keyboards for desktop computer information handling systems have employed an indicator aperture defined within the bounds of a keycap that is selectively lit by an underlying light emitting diode (LED) to indicate the current status of the information handling system, e.g., such as a “Caps Lock”, “Num Lock” or “Scroll Lock” status condition. Such monoblock keyboards are configured with a plastic part having sleeves that receive sliding mechanisms that are attached to the keycaps, i.e., the keycaps are attached to square pillars that slide through corresponding mating holes on the mono-block. Switch mechanisms for the respective keys are positioned below the mono-block. An illumination source in the form of a LED corresponding to each key cap indicator is typically placed on a printed circuit board (PCB) that is positioned below the mono-block. The key stroke length of such a desktop-style keyboard mechanism allows room for placement of a concentric light shield under the keycap adjacent the indicator aperture to allow light from the LED to reach the aperture, while at the same time preventing LED light bleed from under and around the perimeter of the keycap.
For notebook computer applications, the thickness of the keyboard assembly is reduced to a minimum to facilitate the reduced thickness of the notebook computer. As such, the conventional mono-block assembly keyboard is typically not used for notebook computers. Rather, a notebook keyboard typically employs a “scissor mechanism” that employs a set of plastic parts that allow the keycap to traverse up and down in a vertical path. The spring mechanism for this style of notebook keyboard is a rubber dome that collapses and creates switch closure when the rubber dome is fully collapsed. There is insufficient room under such a notebook keycap for placement of a traditional light guide or light mask that is typically utilized in a desktop keyboard assembly.
FIG. 1 illustrates a conventional notebook key device 100 that includes a keycap 102 supported by a collapsible dual lever (scissor) action key mechanism that supports the keycap 102 by utilizing mating lever members 108 and 109 that are secured at one end through a multi-layer keyboard switch membrane (silver ink on Mylar) circuit 106 to a baseplate 104 of a notebook keyboard assembly at a hinge point 130 and to a slidable stopper 132 at the other end. The mating lever members 108 and 109 are configured to pivot downward relative to each other with a scissor-like action when the keycap 102 is depressed, and are provided with a spring mechanism in the form of a resilient rubber dome member 110 that returns the keycap 102 upward to its unpressed position when the keycap 102 is no longer pressed. Rubber dome 110 is also configured to contact and depress circuitry layers together within switch membrane circuit 106 so as to make electrical contact and complete an electrical circuit for a key input signal when keycap 102 is depressed.
FIG. 1 also illustrates indicator aperture and lightguide 118 that is present for transmitting an indicator light to a user of a keyboard assembly that includes the notebook key device 100. For example, keycap 102 may be a “CAPS LOCK” key of a notebook keyboard, and light 120 may be selectively projected from indicator aperture 118 to indicate when the keyboard assembly of the corresponding notebook computer is in “CAPS LOCK” mode. A keycap indicator light emitting diode (LED) 112 is placed in an upward firing position on conductive solder placed on the top surface of the switch membrane circuit 106 in position below the indicator lightguide 118. Indictor LED 112 is encased with an ultraviolet (UV) glue 114 as shown to bond the indicator LED 112 to the solder and switch membrane circuit 106 and to protect the indictor LED 112 from electrostatic discharge (ESD). UV glue 114 is employed to retain the electrical and physical connection of the indictor LED 112 as it cannot be traditionally soldered to a silver-ink/Mylar circuit utilizing a reflow process. UV glue 114 acts as a lens that further scatters light from the indicator LED in a light cone pattern 116 that results in an area 122 of light bleed from the light cone 116 outside the perimeter of the keycap 102.
Current masking techniques require additional hand placed Mylar sections, extra cost, and are inconsistent causing LED's to be obscured and resulting in dim indicators. Light bleed is less of a problem for frame (Chiclet) keyboards due to the shielding they provide, but this type of keyboard also increases cost.
It has also been proposed to couple a separate flexible concentric rubber dome illumination guide to the membrane underneath a notebook keycap over an LED indicator and adjacent to an indicator aperture defined in the keycap. The flexible illumination guide flexes when contacted by downward movement of the keycap. This method may cause the key to feel stiffer than other similar sizes keys.
For backlighting the multiple keycaps of a notebook computer keyboard, it is known to place a light source underneath the baseplate and membrane circuitry of the keyboard and to provide an aperture in the keyboard baseplate and membrane circuit that is aligned with and positioned directly beneath the stabilizer mechanism of each key device for transmitting light to backlight all of the overlying keycaps together at one time. In such a configuration, each keycap may be provided with a translucent section that transmits the backlight through the keycap to illuminate an icon which indicates the identity of each key, i.e., “F” key, “G” key, “Tab” key, etc.